[IMU_Cal] Fixes Runtime Calibration Data Storage

- Corrects NanoSensorCal calibration parameter storage to
  cal.bin/txt.
- Syncs minor code improvements from Google3.

Tip of G3 CL: 197510514
Bug: 79481105
Test: ./load_app.sh and verified calibrations on device.

Change-Id: I8688f88a62aebdbdd92fc37e07108a627167219b
8 files changed